With the development of mobile communications technologies and large-scale deployment of a 3G (3rd generation mobile communications technologies) network, a communications service with large bandwidth and a high rate significantly enhances user experience. However, despite infusion of fresh vigor into the communications service due to large-scale popularization of a smartphone, more challenges to operation of the communications service are caused consequently. Due to a limited throughput, the 3G network cannot support such huge traffic. Currently operating networks have been under great pressure and can satisfy only a part of requirements even for large-scale deployment of LTE (Long Term Evolution) system in future.
Pressure of a communications network is relieved by means of separating user plane data and control plane signaling, that is, a link from an access node to a user equipment is responsible only for transmitting user plane data, and a link from a macro base station to the user equipment is used to transmit control plane signaling that is from the access node to the user equipment. However, some user plane data needs to be transmitted at a macro base station having a high QoS (quality of service) guarantee, whereas some control plane signaling has a relatively low QoS requirement and does not need to occupy a system resource having a high QoS guarantee. Therefore, simply separating user plane data and control plane signaling results in poor QoS of a service and low usage of a system resource.